Biocatalysts, such as cells, immobilized cells, or immobilized enzymes (these may be hereinafter referred to as “biocatalysts”) have advantages in that, for example, reaction processes can be simplified, the reaction products have high purity due to a reduced amount of by-products generated, and highly-reactive materials can also be stably produced due to a mild reaction condition. Thus, biocatalysts are recently used in the production of many compounds.
Biocatalysts, however, cause lowering (deactivation) in the catalytic activity during a reaction. Therefore, methods for regulating the deactivation have been studied in order to enhance the amount of the compound produced per unit amount of catalyst, that is, the productivity of the catalyst (hereinafter, simply referred to as “productivity”). For example, those methods include: a method in which a reaction is carried out at low temperature from the freezing point to 15° C. (Japanese Patent Examined Publication (kokoku) No. 56-38118); a method in which low-concentrated substrates are continuously supplied through a plurality of feed hoppers (Japanese Patent Examined Publication (kokoku) No. 57-1234); a method in which microorganisms or a treated product thereof are processed with an organic solvent (Japanese Patent Application Laying-Open (kokai) No. 5-308980); a method in which a reaction is carried out in the presence of higher unsaturated fatty acids (Japanese Patent Application Laying-Open (kokai) No. 7-265090); and a method in which cells are cross-linked with glutaraldehyde or the like (Japanese Patent Application Laying-Open (kokai) Nos. 7-265091 and 8-154691).